Evidence that gonadal steroids modulate nitric oxide efflux in the medial preoptic area: effects of N-methyl-D-aspartate and correlation with luteinizing hormone secretion

Endocrinology
S PuP S Kalra

Abstract

Several lines of evidence suggest that nitric oxide (NO) is involved in the neuroendocrine control of reproductive function. This study was undertaken to determine 1) NO activity in the medial preoptic area (MPOA) where LHRH- and NO synthase-containing neurons are coextensive; 2) whether N-methyl-D-aspartate (NMDA) receptor activation, which stimulates LHRH release, augments NO activity in the MPOA; and 3) whether NO activation in the MPOA underlies the steroid dependency of NMDA-induced pituitary LH release. As extracellular levels of cGMP in discrete brain sites are a reliable index of basal and stimulated activity of NO, extracellular cGMP levels in the MPOA of freely moving, awake rats were measured by microdialysis in the current study. In the first experiment, the MPOA of intact and castrated male rats were microdialyzed with artificial cerebrospinal fluid at a rate of 5 microliters/min. The basal level of cGMP efflux was determined from the initial seven samples collected at 20-min intervals. The NO response to a single i.v. injection of NMDA (10 mg/kg) or saline was assessed in the next five samples. In the second experiment, the basal and NMDA-evoked NO effluxes in the MPOA of ovariectomized (ovx) and estrogen-treated ...Continue Reading

Citations

May 9, 2014·The Journal of Clinical Investigation·Nicole BellefontaineVincent Prevot
Oct 19, 2004·Physiology & Behavior·Elaine M HullSatoru Sato
Aug 12, 2005·Biology of Reproduction·Xiaoping MaT Rajendra Kumar
May 5, 2005·Nephrology, Dialysis, Transplantation : Official Publication of the European Dialysis and Transplant Association - European Renal Association·Johannes WoitzikFranz Schaefer
Nov 14, 1997·Frontiers in Neuroendocrinology·R J NelsonT M Dawson
Nov 5, 1997·Journal of Pain and Symptom Management·M Anbar, B M Gratt

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